Hitherto, there has been proposed a direct-reduced iron reduction system including an acid gas removing device for removing an acid element in a reducing furnace flue gas corresponding to a synthetic gas discharged from a direct reducing furnace (for example, see Patent Literature 1). In this direct-reduced iron reduction system, the reducing furnace flue gas having a high CO2 partial pressure (for example, 50 kPa to 200 kPa) and discharged from the direct reducing furnace is caused to contact an acid gas absorbent in an acid gas element-absorber so that an acid gas element in the reducing furnace flue gas is removed therefrom. The acid gas absorbent having the acid gas element absorbed thereto is heated in a regenerator to discharge the acid gas element in the acid gas absorbent therefrom so that the acid gas absorbent is regenerated. Further, there is also proposed an acid gas removing facility which removes an acid element contained in a natural gas (for example, see Non Patent-Literature 1).